1. Field of the Invention
The subject invention relates generally to tether positioning systems and tether shape measuring systems and, more particularly, to tether shape measuring systems used for underwater navigation or localization.
2. Description of Related Art
United States Navy and commercial ships face a variety of distributed and challenging threats to the security of both personnel and assets. One such threat is explosive magnetic limpet mines which are attachable to ship hulls, propellers or rudders. In order to minimize this threat, in-water inspections of ships for both maintenance purposes and damage assessment are necessitated. Rapid-response inspections for ship hull mines address the rising need for security, but effective inspections require accurate positioning information to ensure that the entire hull has been thoroughly searched. Effective inspections also require the localization of specific positions on the hull for documentation or a return to the site.
Advanced technologies are emerging for hull inspection and neutralization. However, a major challenge with these advanced systems is navigation during a hull search. Another challenge is the recording of the specific location of an identified threat. Present remotely operated vehicle (ROV) navigation systems are acoustic-based and are difficult to use and have significant performance shortfalls. Such systems typically exhibit poor deployment time, refresh rate, robustness to acoustic harbor noise, and dependability.
In these and other United States Navy applications, an improved method is needed to measure the relative location of a tethered underwater ROV or unmanned undersea vehicle (UUV). Specifically, a need exists for an improved device and method to measuring the relative location of a tethered ROV or UUV for performing ship hull inspections.